Relative positioning and geometry, in particular the parallelism of the pivoting wheel set arbours, determines the precision, working and longevity of timepiece mechanisms.
The utilisation of modular assemblies requires, in particular, perfect precision, because of the stacked independently pre-assembled sub-assemblies.
The concept of extremely high precision modules or cassettes allows large scale production to be combined with high quality goods.
Thus, modular sub-assemblies for timepiece movements are known, from EP Patent Application Nos 11193173.9 and 11193174.7 in the name of ETA SA. The mechanical modules disclosed in these Patent Applications are irreversibly pre-adjusted and assembled to ensure the durability of their settings.
However, in a conventional embodiment, the modules do not always permit a reduction in the number of components, which would both reduce production costs and simplify the assembly plan, enabling mid-level technical personnel to assemble and adjust the most complex functions, while guaranteeing the required geometrical precision.
JP Patent No S5149063 discloses wheel sets including end pivots which pivot in bearings made in the same U-shaped plate. NL Patent No 11224C in the name of Watson discloses a similar configuration.
US Patent Application No. 580046A in the name of Harrington discloses a similar configuration with a U-shaped plate and a parallelism adjustment means using screws.
US Patent Application No. 2582162A in the name of Baermann discloses a magnetic electrical counter bearing including a U-shaped frame containing two aligned two bearings in which the counting wheel set pivots.
CH Patent Application No 488169A in the name of Rego discloses a pivoting device for a compass hand, with a cup bearing carrying two bearings.
DE Patent Application No 2218663A1 in the name of Mueller Schlenker FA discloses balance wheel half bearings with a vertical arbour for the lateral assembly of the balance, closed by a plate including a groove cooperating with a projecting portion of revolution of the balance.
FR Patent Application No 2807160A1 in the name of Denso Corporation discloses a case including aligned bores in which there is guided an arbour including, on one side, a trunnion made of resinous material, and on the opposite side, a hard metal trunnion of smaller diameter to that of the resinous trunnion.